First, it looks like you don't need 1/160 on supporters. They can be loud but don't move that fast. 1/60 will problably do also. Make a testshot first. But then I would worry more about camera-shake at 1/60 you have everything steadily based and mirror-up all the time to reduce vibration.
Once you have your shuttertime you worry about apperture. You don't even want 2.8 for a panorama because of the shallow depth of focus. So 5.5 will be fine, you might even want to go to higher value but that will reduce the light even more. It is a trade-off....
Then ISO, you will be left with no choice other then to increase ISO as far as needed, that's all you can do.....apart from asking the stadium people to turn on some extra light on these supporters.... ;-)
It is always difficult for me to make the compromises between ISO, shutter speed, aperture value at events where you will not have another opportunity. You definitely need time to take some test shots. Though one very important rule is to choose settings that will make the most important part of the image optimal. So, ask yourself which part of the image will draw peoples eyes inward when choosing the final settings.
You probably do not need such a fast shutter speed ( depending upon the circumstances ) and you need to use a higher aperture value to increase the depth of field. I usually use manual focus at the top of a shot where it is darker and contains less contrast. I then switch to auto focus when I reach the areas with more light and contrast. The higher end models of Canon and Nikon cameras auto focus sub systems are better than the regular models.
Try to use a color calibration target with white and 18% grey ( or several grey tones ). Place the target under lighting that is representative of your shot and use the same ISO, shutter speed, and aperture value. If you capture target photos for several light sources, take a photo of the light source immediately after capturing the target so that you can associate the target with the particular lighting. The good news is that the newer stadiums have much better lighting. Unfortunately older stadiums and high school basketball are mixed and yucky. Look at the actual RGB channel numbers for the different target stripes. For example, If one of the channels is significantly higher in the blue channel, there is a blue cast. You may also need to make corrections to the highlights ( white stripe values ) and the midtones ( 18% grey stripe ) seperately. Do your self a big favor and capture several photographs of the target. Color correcting by using the numbers is especially important if you have not calibrated your screen using a color calibration device. http://www.amazon.com/PHOTOVISION-SHOT- … amp;sr=8-3
Here are some examples of settings for games that were photographed with a Canon 5D Mark II
Canon 300mm f/2.8L IS USM ( I was on a shakey platform w/ another person. Otherwise, I would not use 1/160s ) Canon 5D Mark II 1/160s, f/5.6, ISO 3200, manual and auto focus